Current grain holding systems, such as combine grain tank unloading systems of agricultural harvesters, typically consist of single or multiple apparatus, typically, a cross conveyor or conveyors, that feed grain to an unloader conveyor or conveyors, typically a vertical unloader conveyor including an unloader conveyor element, such as an auger, operable for lifting the grain to a generally horizontal conveyor or auger that conveys the grain to a truck or other holding bin. Currently, most cross, vertical and horizontal conveyors or augers can only operate the system at a maximum unload or discharge rate or a shut-off condition.
Agricultural harvesters harvest many different types of grain with varying moisture contents. The unload rate of the grain from the agricultural harvester can vary greatly, depending on the type of grain and the moisture content of the grain. The amount of engine power that is consumed by the unloading system also varies greatly with the type and moisture content of the grain. Generally, corn having a moisture content greater than 25 percent will consume the highest amounts of engine power.
It is highly desirable to maximize the harvesting rate of an agricultural harvester, which typically requires operating the agricultural harvester at its maximum engine power. Unfortunately, due to the increased amount of engine power that is consumed by the unloading system when unloading crops that consume high amounts of power are encountered, such as corn having higher moisture contents, agricultural harvesters may be subjected to operating conditions exceeding maximum engine power, resulting in stalling of the agricultural harvester. In contrast, when unloading crops that consume reduced amounts of power, agricultural harvesters may have additional engine power that is available for use.
Accordingly, there is a need for a method of controlling the conveyance rate of an unloader system of an agricultural harvester based on monitoring a parameter of the harvester's power source, in order to maximize operating performance. For example, the conveyance rate of the unloader system would be decreased in response to the parameter exceeding a predetermined maximum value, and increased in response to the parameter being less than a predetermined maximum value.